Our studies have been focused on the role of the pituitary gland in the regulation of aldosterone secretion and have been designed to localize the area where the unidentified pituitary hormone(s) is derived. The aldosterone response to ACTH and angiotensin II in neurohypophysectomized dogs is quantitatively similar to the response observed in intact control dogs, indicating that the essential pituitary factor(s) is located in the anterior pituitary area. In addition, we have evaluated the roles of the renin-angiotensin-aldosterone and Kallikrein-kinin systems in the regulation of renal function, sodium excretion, and arterial blood pressure.